Pydio

Pydio describes itself as the world's largest open-source file sharing and synchronization project for the enterprise, and the newly announced Pydio 8 boasts a new user experience that the company says extends the platform's lead in design and simplicity, oversight, security and control.
Pydio 8 adds EasyTransfer, a new, intuitive drag-and-drop web interface for organizations in need of an easy-to-use sharing tool. Meanwhile, the aforementioned full UX redesign, based on Google's Material Design principles, builds on Pydio's already smooth and efficient design and simplifies the ability to white-label Pydio.
The new Share Tracking Tool rounds out the new feature set, providing end users with the ability to send a single link to many different people and track exactly who accessed it. Pydio can be deployed on-premises or in a private cloud.
